TH350 Leak: What goes here??

[FlatBlack4Life]

I've got a 71 Cutlass with an original TH350. On the Pass. side of the tranny between where the dipstick tube enters and the cooling lines; there is a space with some type of switch or solenoid that screws into the case. And there's an electrical line off the engine bay harness that goes to this. It's got one connection on it. The pan has a small indentation to aid in removing and installing this. Does anyone knows what goes here?? Because my trans is leaking from there in reverse. I've actually put the car in reverse, and watched it seep out of this switch. I just want to know what it is......I do know it's no the Kickdown cable hook up.



Look directly under the cooling line humps...and this is where the part goes in.

[carkrazy1987]

not exactly sure but could be a guess reverse lock out type switch, or maybe reverse switch for lights. i dunno justa guess.

[Vince@Meanstreets]

In 71' GM cali cars had a system to disable the vacuum advance when in certain gears. Referred to as "spark controls" it used a switch to ground the circuit to a solinoid that would either allow or block vacuum to the vacuum advance can on the distributer.

If I remember correctly it is a discontinued part. Might be found used. Same switch used by all GM from 71-75 vehicles.

Note: it is a 1/8" npt port which happens to be a common plug size.